1. Field of the Invention
The present invention relates to design and production methods of a gas turbine.
2. Description of the Related Art
In recent years, new types of turbines such as humid air turbines injecting moisture into the intake air of the compressor and blast furnace gas firing gas turbines using low-calorie blast furnace gas as the fuel are emerging as derivative models of gas turbines. In cases where a derivative model is designed or produced based on a standard type of gas turbine that uses lamp oil, light oil, natural gas or the like as the fuel with no humidification of the intake air (reference model) at a low cost, it is desirable to reuse as many components of the reference model (i.e., divert as many components from the reference model) as possible and thereby reduce the number of components newly developed.
Meanwhile, if the compressor flow rate in a humid air turbine or a blast furnace gas firing gas turbine is made equal to that in the reference model, the turbine flow rate increases in comparison with the reference model. Specifically, since the humid air gas turbine supplies moisture to the downstream side of the compressor, the turbine flow rate increases correspondingly in comparison with the reference model. Also in the blast furnace gas firing gas turbine, due to the use of blast furnace gas as low-calorie fuel, a greater amount of fuel is necessary compared to cases where a common type of gas turbine fuel (natural gas, petroleum, etc.) is used, and consequently, the turbine flow rate increases correspondingly in comparison with the reference model. Therefore, in humid air turbines and blast furnace gas firing gas turbines, the turbine has to be newly designed and it is impossible to simply reuse components of the reference model.
To deal with this problem, there has been proposed a method that reduces the outer radius of the compressor channel to decrease the annulus area of the compressor channel, thereby reduces the compressor flow rate, and thereby makes the turbine flow rate equivalent to that in the reference model (see U.S. Pat. No. 7,937,947, for example).